Bikini Bottom Genetics Name ___________________________ 

Scientists at Bikini Bottoms have been investigating the genetic makeup of the organisms in this community. 
Use the information provided and your knowledge of genetics to answer each question. 

1. For each genotype below, indicate whether it is a heterozygous (He) OR homozygous (Ho). 
TT _____ Bb _____ DD _____ Ff _____ tt _____ dd _____ 
Dd _____ ff _____ Tt _____ bb _____ BB _____ FF _____ 

Which of the genotypes in #1 would be considered purebred? _______________________________ 
Which of the genotypes in #1 would be hybrids? __________________________________________ 

2. Determine the phenotype for each genotype using the information provided about SpongeBob. 
Yellow body color is dominant to blue. 
YY _________________ Yy _________________ yy _________________ 
Square shape is dominant to round. 
SS _________________ Ss _________________ ss _________________ 

3. For each phenotype, give the genotypes that are possible for Patrick. 
A tall head (T) is dominant to short (t). 
Tall = ________________________ Short = __________________________ 


Pink body color (P) is dominant to yellow (p). 
Pink body = ___________________ Yellow body = _____________________ 


4. SpongeBob SquarePants recently met SpongeSusie Roundpants at a dance. SpongeBob is heterozygous 
for his square shape, but SpongeSusie is round. Create a Punnett square to show the possibilities that would 
result if SpongeBob and SpongeSusie had children. HINT: Read question #2! 
A. List the possible genotypes and phenotypes for their children. 
B. What are the chances of a child with a square shape? ____ out of ____ or ____% 
C. What are the chances of a child with a round shape? ____ out of ____ or ____% 
5. Patrick met Patti at the dance. Both of them are heterozygous for their pink body color, which is dominant 
over a yellow body color. Create a Punnett square to show the possibilities that would result if Patrick and 
Patti had children. HINT: Read question #3! 
A. List the possible genotypes and phenotypes for their children. 
B. What are the chances of a child with a pink body? ____ out of ____ or ____% 
C. What are the chances of a child with a yellow body? ____ out of ____ or ____% 
Worksheet created by T. Trimpe 2003 http://sciencespot.net/ 


6. Everyone in Squidwards family has light blue skin, which is the dominant trait for body color in his 
hometown of Squid Valley. His family brags that they are a purebred line. He recently married a nice girl 
who has light green skin, which is a recessive trait. Create a Punnett square to show the possibilities that 
would result if Squidward and his new bride had children. Use B to represent the dominant gene and b to 
represent the recessive gene. 
A. List the possible genotypes and phenotypes for their children. 
B. What are the chances of a child with light blue skin? ____% 
C. What are the chances of a child with light green skin? ____% 
D. Would Squidwards children still be considered purebreds? Explain! 
7. Assume that one of Squidwards sons, who is heterozygous for the light blue body color, married a girl 
that was also heterozygous. Create a Punnett square to show the possibilities that would result if they had 
children. 
A. List the possible genotypes and phenotypes for their children. 
B. What are the chances of a child with light blue skin? ____% 
C. What are the chances of a child with light green skin? ____% 
8. Mr. Krabbs and his wife recently had a Lil Krabby, but it has not been a happy occasion for them. Mrs. 
Krabbs has been upset since she first saw her new baby who had short eyeballs. She claims that the hospital 
goofed and mixed up her baby with someone elses baby. Mr. Krabbs is homozygous for his tall eyeballs, 
while his wife is heterozygous for her tall eyeballs. Some members of her family have short eyes, which is 
the recessive trait. Create a Punnett square using T for the dominant gene and t for the recessive one. 
A. List the possible genotypes and phenotypes for their children. 
B. Did the hospital make a mistake? Explain your answer. 
Worksheet created by T. Trimpe 2003 http://sciencespot.net/ 


Bikini Bottom Genetics 
Answer Key 

1. 
Purebreds -TT, DD, BB, FF, ff, dd, bb, tt 
Hybrids -Dd, Bb, Ff, Tt 

2. 
3. 
Tall-TT or Tt Short-tt 
Pink -PP or Pp Yellow  pp 
4. 
A. SS -square shape, Ss -square shape, and ss -round shape 
B. 2outof4or50% 
C. 2outof4or50% 
NOTE: Some of your students may feel that the roundpants gene should be the dominant trait as SpongeBobs TV parents are 
both roundpants. However, these are only his parents on the TV show and his real parents are both heterozygous for squarepants. 

5. 
A. PP -pink body, Pp -pink body, and pp -yellow body 
B. 3outof4or75% 
C. 1outof4or25% 
6. 
A. Bb -light blue skin 
B. 100% 
C. 0% 
D. Squidwards children would not be considered purebred, since each would have a 
gene pair made up of a dominant gene and a recessive gene. 
7. 
A. TT -tall eyeballs or Tt -tall eyeballs 
B. The hospital must have made a mistake, since the genotype tt would not be 
possible based on the genotypes of Mr. and Mrs. Krabbs. 
NOTE: Students may come up with other possible scenarios, such as 
Mr. Krabbs not really a homozygous tall-eyed crab or a mutation. A few of 
my students suggested that Mr. Krabbs might not be the father! 
NOTE: Some of your students may comment that Mr. Krabbs had a whale as a daughter. However, this was only for 
the TV show. He is happily married to a beautiful crab in real life and has beautiful crab children. (Ok, so its not 
real life!) 

Worksheet created by T. Trimpe 2003 http://sciencespot.net/ 


